Question

您好我使用POI创建了Excel工作表。我已经在下一个方面添加了图片（jpg文件）：

Workbook wb = new HSSFWorkbook();
CreationHelper helper = wb.getCreationHelper();
//...
InputStream is = new FileInputStream("img.jpg");
byte[] bytes = IOUtils.toByteArray(is);
int picIdx = wb.addPicture(bytes, Workbook.PICTURE_TYPE_JPEG);
Drawing drawing = sheet.createDrawingPatriarch();
ClientAnchor anchor = helper.createClientAnchor();
anchor.setCol1(5);
anchor.setRow1(5);
Picture pict = drawing.createPicture(anchor, picIdx);
pict.resize();

现在我希望图片适合那个单元格，但我不想改变它的宽高比。我可以放入调整大小的尺度是相对于细胞，显然可以有不同的比例。我试图计算尺度，但问题是，我无法获得或设置像素中的行高，仅在pt中，我无法计算单元格比例bc i can can＆t获取相同单位的宽度和高度......有什么建议吗？

Answer 1

POI中有一个Units类，它提供像素和点之间的转换这里有一些方法可能有助于设置单元格的宽度和高度。

1.Centimeters to Pixels

public static int cmToPx(double cm) {
    return (int) Math.round(cm * 96 / 2.54D);
}

96是我的显示器的DPI（请从dpilove查看）和1英寸= 2.54厘米

2.Centimeters to RowHeight

public static int cmToH(double cm) {
    return (int) (Units.pixelToPoints(cmToPx(cm)) * 20); //POI's Units
}

用法：sheet.setDefaultRowHeight(cmToH(1.0))
参考：HSSFRow#getHeightInPoints

将高度设置为“缇”或1点20分。

3.Centimeters to ColumnWidth

public static int cmToW(double cm) {
    return (int) Math.round(((cmToPx(cm) - 5.0D) / 8 * 7 + 5) / 7 * 256);
}

用法：sheet.setColumnWidth(cmToW(1.0))
使用(px - 5.0D) / 8将像素转换为excel宽度的点。（在excel中拖动列的宽度时，像素和点将显示在光标周围）
参考：HSSFSheet#setColumnWidth

设置宽度（以字符宽度的1/256为单位）

Excel使用以下公式（OOXML规范的第3.3.1.12节）：

// Excel width, not character width
width = Truncate([{Number of Visible Characters} * {Maximum Digit Width} + {5 pixel padding}]/{Maximum Digit Width} * 256) / 256

以Calibri字体为例，11磅字体的最大数字宽度为7像素（96 dpi）。如果将列宽设置为八个字符宽，例如setColumnWidth（columnIndex，8 * 256），然后可见字符的实际值（Excel中显示的值）来自以下等式：

Truncate([numChars * 7 + 5] / 7 * 256) / 256 = 8;

使用XSSFClientAnchor调整图片大小以填充单元格并保持其比例：

// set padding between picture and gridlines so gridlines would not covered by the picture
private static final double PADDING_SIZE = 10;
private static final int PADDING = Units.toEMU(PADDING_SIZE);

/**
 * Draw Image inside specific cell
 *
 * @param wb workbook
 * @param sheet sheet
 * @param cellW cell width in pixels
 * @param cellH cell height in pixels
 * @param imgPath image path
 * @param col the column (0 based) of the first cell.
 * @param row the row (0 based) of the first cell.
 * @param colSize the column size of cell
 * @param rowSize the row size of cell
 */
public static void drawImageInCell(SXSSFWorkbook wb, SXSSFSheet sheet, int cellW, int cellH,
      String imgPath, int col, int row, int colSize, int rowSize) throws IOException {
    Path path = Paths.get(imgPath);
    BufferedImage img = ImageIO.read(path.toFile());
    int[] anchorArray = calCellAnchor(Units.pixelToPoints(cellW), Units.pixelToPoints(cellH),
       img.getWidth(), img.getHeight());
    XSSFClientAnchor anchor = new XSSFClientAnchor(anchorArray[0], anchorArray[1], anchorArray[2],
        anchorArray[3], (short) col, row, (short) (col + colSize), row + rowSize);
    int index = wb.addPicture(Files.readAllBytes(path), XSSFWorkbook.PICTURE_TYPE_JPEG);
    sheet.createDrawingPatriarch().createPicture(anchor, index);
}

/**
 * calculate POI cell anchor
 *
 * @param cellX cell width in excel points
 * @param cellY cell height in excel points
 * @param imgX image width
 * @param imgY image height
 */
public static int[] calCellAnchor(double cellX, double cellY, int imgX, int imgY) {
    // assume Y has fixed padding first
    return calCoordinate(true, cellX, cellY, imgX, imgY);
}

/**
 * calculate cell coordinate
 *
 * @param fixTop is Y has fixed padding
 */
private static int[] calCoordinate(boolean fixTop, double cellX, double cellY, int imgX, int imgY) {
    double ratio = ((double) imgX) / imgY;
    int x = (int) Math.round(Units.toEMU(cellY - 2 * PADDING_SIZE) * ratio);
    x = (Units.toEMU(cellX) - x) / 2;
    if (x < PADDING) {
        return calCoordinate(false, cellY, cellX, imgY, imgX);
    }
    return calDirection(fixTop, x);
}

/**
 * calculate X's direction
 *
 * @param fixTop is Y has fixed padding
 * @param x X's padding
 */
private static int[] calDirection(boolean fixTop, int x) {
    if (fixTop) {
        return new int[] { x, PADDING, -x, -PADDING };
    } else {
        return new int[] { PADDING, x, -PADDING, -x };
    }
}

Answer 2

我正在使用Base64图像数据，并且这样做是这样的，对我来说，它会在给定的col / row处添加并正确调整其大小，而且我也不想容纳它可以左右固定的单元格：< / p>

    byte[] imageBase64Data = base64DataString.getBytes();
    byte[] imageRawData = Base64.getDecoder().decode(imageBase64Data);

    int imgWidth = 1920; // only initial if not known
    int imgHeight = 1080; // only initial if not known

    try {
        BufferedImage img = ImageIO.read(new ByteArrayInputStream(imageRawData));
        imgWidth = img.getWidth();
        imgHeight = img.getHeight();
    } catch (IOException e) {
        e.printStackTrace();
    }

    int pictureIdx = workbook.addPicture(imageRawData, Workbook.PICTURE_TYPE_PNG);

    CreationHelper helper = workbook.getCreationHelper();
    Drawing drawing = sheet.createDrawingPatriarch();
    ClientAnchor anchor = helper.createClientAnchor();

    anchor.setCol1(desiredCol);
    anchor.setRow1(desiredRow);
    Picture picture = drawing.createPicture(anchor, pictureIdx);
    picture.resize(0.7 * imgWidth / XSSFShape.PIXEL_DPI, 5 * imgHeight / XSSFShape.PIXEL_DPI);

Apache POI Excel工作表：在保持其比例的同时调整图片大小

2 个答案: